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Structural, morphological, optical, and electrochemical properties of Zn-doped CeO2/rGO nanocomposites
(2025-04-01)
Utara, Songkot
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Salidkul, Nuchjaree
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Karaphun, Attaphol
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Sonsupap, Somchai
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Chanlek, Narong
Metal-doped cerium oxide has recently attracted the interest of researchers worldwide because of its various applications in different fields such as supercapacitors, high-sensitivity electrodes or photocatalytic. Metal-doped cerium oxide can be improved utilizing a variety of metals and composites with enhanced conductivity, which advances materials science in semiconductor processing. In this study, undoped and Zn-doped CeO<inf>2</inf> nanoparticles at 5, 10, 15, and 20 at.% were reacted with reduced graphene oxide (rGO) using a hydrothermal method. They were heated at 150 °C for 12 h and then processed in an ultrasonic reactor (20 kHz) at 25 ± 1 °C. Their structural, morphological, elemental, optical, and electrochemical properties were systematically characterized. The calculated average crystallite sizes of CeO<inf>2</inf> peaks ranged from 4.60 ± 0.2 to 12.0 ± 0.4 nm. These samples exhibited a single CeO<inf>2</inf> phase corresponding to a face-centered cubic structure, except for 20 at.% Zn-doped CeO<inf>2</inf>/rGO, which presented a ZnO phase. The samples had lower band gap values than expected for undoped CeO<inf>2</inf> nanoparticles, higher valence states due to their Ce3+/Ce4+ ratios, and a large surface area, 242 m2/g, due to Zn-doping in CeO<inf>2</inf> samples. The highest specific capacitance values achieved were 88.49 F/g at 5 mV/s and 134.01 F/g at 0.5 A/g for undoped CeO<inf>2</inf>/rGO. Zn-doping resulted in decreased capacitive behavior with specific capacitance values in the range of 70.78–81.00 F/g at 5 mV/s and 79.24–101.43 F/g at 0.5 A/g. This study for synthesizing Zn/CeO<inf>2</inf>/rGO ternary nanocomposites produced materials with improved band gaps, valence states of Ce3+/Ce4+ ratios, and greater surface area for improved electrocatalytic performance.
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Synthesis and electrochemical properties of activated lignite carbons-reduced graphene oxide nanocomposites symmetric supercapacitors
(2024-08-15)
Tuichai, Wattana
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Karaphun, Attaphol
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Phrompet, Chaiwat
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Chanlek, Narong
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Swatsitang, Ekaphan
Ultra-fast chargeable or rechargeable symmetric carbon-based supercapacitors (SCSs) with high capacity, inexpensive, and non-flammability have attracted much attention for electronics and energy storage devices. However, improving both high redox reaction and ion transport/diffusion processes by enhancing high energy storage performance and rapid ion/electron transport SCSs electrode materials remains challenging. Herein, we presented a successful preparation of activated lignite carbons-reduced graphene oxide (ALC-rGO) nanocomposite (NCp) with the ALC:rGO ratio of 80:20 wt% by a one-pot hydrothermal for high electrochemical performance. Importantly, the matrix of ALC-rGO NCp was primary amorphous carbon with hexagonal graphitic layers and pore structures of plentiful micropores and mesopores. Remarkably, the ALC-rGO NCp electrode exhibited a maximum specific capacitance (C<inf>sc</inf>) of 152.12 F/g at 0.5 A/g. Interestingly, the SCSs-ACL-rGO device could illustrate a good performance at a potential voltage of 1.8 V with C<inf>sc</inf> of 50.90 F/g at 1 A/g and capacity retention of 96.0 % at 5 A/g after 2,000 cycles GCD test.
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The Mechanical and Thermal Properties of Cement CAST Mortar/Graphene Oxide Composites Materials
(2022-12-01)
Janjaroen, Thidatip
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Khammahong, Sunisar
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Tuichai, Wattana
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Karaphun, Attaphol
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Phrompet, Chaiwat
This paper presents the influence of the graphene oxide (GO) sheet contents at conditions of 0, 0.01, 0.03, 0.05, and 0.1 wt% on the mechanical and thermal properties of GO/CAST 11 LW mortar (GMT) composites for heat insulating brick. The GMT composites were prepared by a simple mixing method. The structure of GMT composites was investigated by X-ray diffraction (XRD) and Raman spectroscopy (Raman) techniques. The small grain sizes of GMT composites were confirmed by transmission electron microscopy (TEM). The mechanical properties of GMT composites are increased with increasing GO contents. A lot of functional groups in GO such as carboxylic acid reacted with a calcium silicate hydrate, CaH<inf>2</inf>O<inf>4</inf>Si (CSH), calcium hydroxide, Ca(OH)<inf>2</inf> (CH) and Ettringite, and Ca<inf>6</inf>[Al(OH)<inf>6</inf>]<inf>2</inf>(SO<inf>4</inf>)<inf>3</inf>·26H<inf>2</inf>O (CA) phases in the mortar, which can be considered good mechanical properties in the GMT composites. The heat insulation values of GMT composites were improved by the interaction with the CSH, CH, and CA phases in the cement mortar on the surface of GO. The highest compressive and tensile strengths and low heat transfer rate of about 0.465 W/min were observed at 0.05 of GO (GMT_0.05) composites in the curing age of 7 days. Thus, a new pathway of GMT composites can be prepared by a simple mixing method to significantly improve the mechanical and thermal properties of mortar GMT composites.
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Characterization and electrochemical properties of CuO–Cu2O@rGO nanocomposite synthesized by a seed-mediated growth process
(2022-04-01)
Wongjom, Poramed
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Tuichai, Wattana
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Karaphun, Attaphol
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Phrompet, Chaiwat
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Daengsakul, Sujittra
A CuO–Cu<inf>2</inf>O@rGO nanocomposite (CuO–Cu<inf>2</inf>O@rGO NCP) has been successfully prepared through a seed-mediated growth process. X-ray diffraction (XRD) analysis results indicated a monoclinic phase of CuO–Cu<inf>2</inf>O@rGO NCP with space group C2/c. Transmission electron microscopy (TEM) revealed agglomeration of the CuO and Cu<inf>2</inf>O nanoparticles in the rGO sheet matrix. The interaction of CuO–Cu<inf>2</inf>O@rGO NPC resulted from the aggregation and overlapping of CuO and Cu<inf>2</inf>O nanoparticles owing to the influence of a seed-mediated growth process. The electrochemical properties of the CuO–Cu<inf>2</inf>O@rGO NPC electrode indicate the storage of energy at the surface through a pseudo-capacitive mechanism. The specific capacitance at a current density of 0.5 A g−1 and the average percentage capacity retention after 1000 cycles of a CuO–Cu<inf>2</inf>O@rGO electrode at a current density of 10 A g−1 were evaluated as 125.54 F g−1 and 89.87 ± 3.30%, respectively. In the CuO–Cu<inf>2</inf>O@rGO electrode, the incorporated rGO affects the electrical conductivity and the synergistic interactions in charge–discharge processes. Interestingly, these results showed that the material was synthesized through a seed-mediated growth process and reveal the key factors that determine the combination and volume expansion of the reversible redox transition between Cu+ and Cu2+ during charge–discharge processes.
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Improved dielectric properties of PVDF polymer composites filled with Ag nanomaterial deposited reduced graphene oxide (rGO) hybrid particles
(2022-01-01)
Tuichai, Wattana
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Karaphun, Attaphol
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Ruttanapun, Chesta
We report a method to improve the dielectric constant (ε′) of polyvinylidene fluoride (PVDF) composites by using a low content of Ag nanomaterials deposited reduced Graphene Oxide (rGO) Hybrid Particles (Ag-rGO HPs). The Ag-rGO HPs are prepared by a reaction between silver nitrate and ethylene glycol in a seed-mediated growing process. The dispersion of Ag nanomaterials was completely homogeneous on the surface of rGO nanosheets with particle sizes of 5.765 ± 0.189 nm. The Ag-rGO HPs/PVDF composites were produced by a liquid–phase assisted dispersion and hot-pressing methods. The high ε′ at 103 Hz for Ag-rGO/PVDF composites with f<inf>Ag-rGO</inf> 7.8, and 11.9 vol% was 153 and 683, respectively. The best-fitting curve was completely achieved in percolation theory by adjusting f<inf>c</inf> = 14 vol%. The high ε′ (683 at 1 kHz) of Ag-rGO/PVDF could be explained by Maxwell Wagnare Sillars interfacial polarization and micro-capacitor due to the formation of a sandwich between Ag-rGO and PVDF.
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Influence of free electron charge and free extra framework anions in calcium aluminate@ rGO (CA@ rGO) cement composites with enhanced dielectric and electrochemical properties
(2021-10-01)
Ruttanapun, Chesta
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Phrompet, Chaiwat
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Tuichai, Wattana
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Karaphun, Attaphol
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Daengsakul, Sujittra
Nowadays, the metal oxide-based composites loaded with reduced graphene oxide (rGO) nano sheets are believed to enhance both the electrochemical and dielectric properties. In this study, therefore, the effect of rGO loading contents on the calcium aluminate (CA), namely CA@ rGO, cement composites with high dielectric and electrochemical properties is presented. CA@ rGO composites were successfully synthesized via a simple direct mixing of CA cement with various contents of graphene oxide (GO) precursors followed by a conventional thermal reduction method. Based on XRD and Raman spectroscopy results, all prepared CA@ rGO composites clearly confirmed both the structure of the pristine CA cement as well as the complete conversion of GO precursors to rGO after thermal reduction, and the existence of rGO nano sheets on the surface of CA@ rGO composites. The impedance value results revealed that the enhancement of a high dielectric constant was achieved in the CA@ rGO composites due to both typical interface polarization and the micro-capacitor of CA cement and rGO nano sheets. Meanwhile, the prepared CA@ rGO-4 composite electrode exhibited the highest of electrochemical double-layer capacitive behavior with the specific capacitance (C<inf>sc</inf>) value of 79.33 F g−1 at 0.2 A g−1. The enhanced super-capacitive performance of CA@ rGO composite can be improved by the synergistic effect of free electron transfer and electron diffusion between the CA cement interface and rGO nano sheets.
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Dielectric and electrochemical properties of hybrid Pt nanoparticles deposited on reduced graphene oxide nanoparticles /poly (vinylidene fluoride) nanocomposites
(2021-06-01)
Karaphun, Attaphol
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Tuichai, Wattana
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Chanlek, Narong
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Sriwong, Chaval
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Ruttanapun, Chesta
Nano-sized platinum (Pt) materials deposited on reduced Graphene Oxide (rGO) nanosheets (hybrid Pt-rGO nanoparticle) were prepared by the seed-mediated growing process using 20 wt% of Pt nanomaterials in rGO suspension. Dielectric properties of hybrid Pt-rGO nanoparticles/poly (vinylidene fluoride) nanocomposites (Pt-rGO/PVDF nanocomposites) were synthesized by a liquid–phase assisted dispersion and hot–pressing methods with different volume fractions (f) of hybrid Pt-rGO nanoparticle loading PVDF nanocomposites. The observed particle size of Pt nanomaterials deposits on rGO nanosheets was 5 nm. The dielectric constant (ε′) of Pt-rGO/PVDF nanocomposites was increased with increasing hybrid Pt-rGO nanoparticle. The volume fraction f<inf>Pt-rGO</inf> ≈0.0786 exhibited excellent ε′ ≈ 86 with very low loss tangent (tanδ) ≈ 0.021 at 1 kHz. High dielectric properties of Pt-rGO/PVDF composite should be ascribed to combination of the micro-capacitor and Maxwell–Wagner–Sillars (MWS) effects. Electrochemical properties of speciﬁc capacitances (C<inf>sc</inf>) and capacity retention of hybrid Pt-rGO nanoparticle electrode were investigated by the cyclic voltammetry and the galvanostatic charge-discharge. Interestingly, the hybrid Pt-rGO nanoparticle electrode displayed maximum C<inf>sc</inf> value of 169.8 F g−1 at the current densities of 0.25 A g−1. This was due to the occurrence of various oxygen functional groups in the rGO- and Pt+ ions as contributing to form of pseudo-capacitance in hybrid Pt-rGO nanoparticle.
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The influence of annealing on a large specific surface area and enhancing electrochemical properties of reduced graphene oxide to improve the performance of the active electrode of supercapacitor devices
(2021-02-01)
Karaphun, Attaphol
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Phrompet, Chaiwat
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Tuichai, Wattana
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Chanlek, Narong
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Sriwong, Chaval
Influence of annealing process on microstructure, large specific surface area and enhancing electrochemical properties to synthesize reduced graphene oxide (rGO) for the supercapacitor electrode was investigated. Thermal annealing process of rGO (rGO_An) was improved crystallinity and electrical conductivity. BET analysis of rGO_An sample exhibited the occurrence of large mesoporous and macrospores with a huge specific surface area of 672.1 m2/g and an average pore size of 46.2 nm, resulting the rGO_An sample activates more electrodes than rGO sample. Specific capacitance (C<inf>s</inf>) was affected by improving conductivity through annealing process with an excellent cycling stability after 750 cycles for GCD tests of 97.32%, which exhibited the highest value and an average energy density of 412.096 F g−1 and 74.5 Wh kg−1, respectively at 1 A g−1. Thus, annealing process can occur with large mesoporous and macrospores pore improving the electrical conductivity and stability to be applied as an electrode in supercapacitor.
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Enhancing the supercapacitor performance of NiCo2O4 microflowers by reduced graphene oxide nano-sheets
(2021-01-28)
Saei, Worawee
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Buranasiri, Prathan
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Karaphun, Attaphol
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Ruttanapun, Chesta
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Sriwong, Chaval
This work presented the preparation and supercapacitor performance of a spinel nickel-cobalt oxide (NiCo2O4) microflowers mixed with nano-sized reduced graphene oxide (rGO) sheets. The hybrid material (NiCo2O4/rGO), pure NiCo2O4 and nano-sized rGO samples were characterized and confirmed by several techniques, such as XRD, SEM and EDS. The supercapacitive properties of all prepared samples were also studied using an electrochemical measurement technique (CV and GCD). The results revealed that the NiCo2O4/rGO (484.1 F.g-1) hybrid electrode exhibited much higher specific capacitance than those of pristine NiCo2O4 (358.3 F.g-1) and nano-sized rGO (113.8 F.g-1) electrodes, respectively. Hence, this work indicates that the supercapacitor performance of NiCo2O4 mixed rGO hybrid materials is more superior to the pure NiCo2O4 microflowers and nano-sized rGO sheets.
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Ag nanomaterials deposited reduced graphene oxide nanocomposite as an advanced hybrid electrode material for Asymmetric Supercapacitor device
(2020-12-30)
Tuichai, Wattana
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Karaphun, Attaphol
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Ruttanapun, Chesta
Asymmetric Supercapacitor (ASC) was effectively fabricated using CR 2032-coin cell based on the positive electrode of the hybrid Ag@rGO nanocomposite and the negative electrode of reduced Graphene Oxide (rGO) material with polyvinyl alcohol (PVA)/6 M KOH electrolyte. The Ag@rGO nanocomposite was prepared through a seed-mediated growing process by a 10 wt% of Ag nanomaterials deposits in suspension rGO 90 wt% which presented a specific capacitance value of 65.9 F g−1 at current density of 0.5 A g−1. Moreover, the rGO electrode with a 5 mg/mL concentration was synthesized by the modified Hummers’ method and revealed a high specific capacitance value of 317.3 F g−1 at current density of 0.5 A g−1. Interestingly, the ASC assembly of Ag@rGO//rGO hybrid energy-storage device provided a wide voltage window of 0.0–1.4 V and showed a specific capacitance (C<inf>sc</inf>) value of 44.17 F g−1 at current density of 3 A g−1. This hybrid energy-storage device indicated specific energy density (E<inf>sp</inf>) of 11.09 W h kg−1 and specific power density (P<inf>sp</inf>) of 2.67 kW kg−1, respectively. It also showed a good cycle stability of 81.5%. The capacitance retention finished at 500 cycles.

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